This invention relates to a method of preparing a heat recoverable thermoelastic plastic foam derived from the reaction of poly (vinyl chloride) homopolymers and copolymers with polymerizable polyfunctional allyl or vinyl compounds.
Many processes are known in the art for preparing a variety of foamed products. One such process, as taught in U.S. Pat. No. 3,770,662, is a process for preparing a foamed fluroelastic article which comprises precuring a material consisting of a blowing agent, a polyfunctional methacrylate crosslinking agent, and an organic peroxide, and then blowing this material to produce a multitude of small cells therein. Another process for preparing foamed products is shown in U.S. Pat. No. 3,267,051, which teaches a method for manufacturing rigid cellular products which consist of a saturated halogenated hydrocarbon, a mixture containing polyvinyl chloride, a polyisocyanate, a swelling agent, and at least one vinylidenic monomer. The method of preparing this rigid cellular product comprises several steps including heating under pressure and cooling under pressure.
Other methods for preparing foamed products are found in U.S. Pat. No. 3,308,074 and U.S. Pat. No. 3,413,244. These methods require, as do many others in the prior art, a multistep process using pressure and blowing agents.